So it's cured and ready. I knock it out of the mold, uninstall the existing engine mount, and prepare this one for install. It looks perfect.
It's installed, and I torque the nuts to 65 ft-lb.
A few minutes later, I'm sitting in the car about to turn it on, talking on the phone.
BANG
I get out of the car and notice this new dent in the hood.
I knew immediately what happened. The studs I used were not the right material/temper, and couldn't handle the tension. The only studs I could find in the size I needed were "Class 45H". I asked the fastener company what it was comparable to, but they weren't sure. Turns out, it "very specifically applies to fasteners not under tensile stress." Other articles state "Any application of tensile stress goes against the intended use of the screw and can lead to failure." They are supposed to be used as set screws only.
I reinstalled the OEM mount for now. Ordered class 12.9 threaded rod which I'll have to cut to size. Will probably try it on the next chassis, and just keep the OEM installed for now on this car.